Field of the Invention
The present invention relates generally to systems for monitoring the listening habits of radio users, and more particularly to an inexpensive system for providing a highly accurate record of the amounts of time each of a number of radio stations were listened to by a radio user over an extended period of time.
There is a long history of devices designed to monitor viewing habits of people watching television, with such devices generally designed to provide information used to generate ratings used by purchasers of commercials on particular television programs. Virtually all of these devices operate using one of four basic operating techniques.
The first technique, which is the oldest, sends information regarding which channel the receiver is tuned to from the viewers' homes directly to a central monitoring station where the tuning information is evaluated. This approach is illustrated by U.S. Pat. Nos. 3,058,065, to Freeman et al, and 4,048,562, to Haselwood et al. The primary disadvantage of these systems is their extremely high cost. While the television networks are able to afford such an expensive method of determining ratings, most radio stations, particularly those in smaller local markets, simply can't afford to pay for expensive systems such as these, and the use of such systems has accordingly been restricted to use in compiling ratings information for large and wealthy customers such as national television networks.
The second method used is to have the transmitting stations modulate a code signal onto their transmission signals to allow this coded signal to be used at the receivers to provide an indication of the program being monitored in the viewers' homes. Examples of such systems are found in U.S. Pat. Nos. 3,492,577, to Reiter et al, and 4,025,841, to Haselwood et al. It is important to note that the coded signal is inserted periodically, and may be used once per program or at a higher repetition rate per program for longer programs.
It is here that the fundamental difference between radio and television programming is illustrated. Television is program oriented, while radio is largely song oriented, which means that while if it can be determined that a viewer is listening to a television program at any point during the program, the viewer will likely watch the entire program, a radio listener is likely to change stations on a song basis. Since many radio listeners will change stations to avoid listening to a song they do not like, the phenomenon of changing stations on an irregular and unpredictable basis is unique to radio programming, with the possible exception of talk radio programs, which constitute a definite minority of radio programming.
It is therefore apparent that the use of a periodic signal sent by radio transmitters to radio receivers to determine ratings is not nearly as practical as it is in television broadcasts. In addition, another serious problem is present in this technique. While the system of using different codes for different transmitters is practical for use with a small number of stations, such as the three large television networks, it is not acceptable in radio, where in large markets there are literally dozens of radio stations. It is unlikely that a large percentage of these stations could be convinced to buy the necessary transmission equipment, particularly since many radio stations operate on a budget which is miniscule in comparison to that of a television network.
The third, and most popular, technique is to record the time of all channel changes, together with the channel. This type of device is taught in U.S. Pat. Nos. 3,453,641, to Rahmel, 3,906,450, to Prado, Jr., 4,258,386, to Cheung, and 4,361,851, to Asip et al, and is used uniquely for television applications. The primary reason this type of system is not used for radio is its complexity of design, which is synonymous with a degree of cost unacceptible to radio stations for the reasons given above. In addition, since the radio station listened to is likely to be changed far more frequently than is a television station, the amount of data collected will be unacceptably large, and more expensive to process.
The fourth technique is to record information regarding the channel periodically, as demonstrated by U.S. Pat. No. 3,849,729, to Van Baggem. The Van Baggem device is, unfortunately, program oriented, recording the channel selected once every 15 minutes, a duration impractical in radio ratings. In addition, the Van Baggem device is cumbersome in construction, periodically turning on a motorized recording unit to store the information. The Van Baggem device is also expensive, making the fourth technique disadvantageous for the reasons given previously.
It is thus apparent that the four techniques used to measure television ratings are either not practicable for measuring radio ratings, or too expensive to be utilized by most radio stations, or both. The technique currently in use to measure radio ratings is that of evaluating a large number of listening logs kept by selected listeners representing a cross-section of the listening audience. While these logs will provide information relatively inexpensively, the validity of a system depending on accurate recording of information by listeners is inherently suspect, particularly when radio stations are apt to be changed so often.
Therefore, there exists a clear need for an accurate system uniquely designed for use in gathering information used in radio ratings. Such a system must be relatively inexpensive, both in construction and in use. Information derived directly from radio use must be accurately stored for an extended period of time, with the collection of this information being simple and easily accomplished. The system must accurately indicate listening periods determined by song length rather than by the substantially longer program length of television. The system should be installable on any radio without interference with normal operation, and must distinguish between AM and FM programming. Finally, the system must be one which will inspire the confidence of the industry, and present the aforementioned advantages without substantial disadvantage.